Component for a gas turbine engine with a film hole

Abstract

A component is provided and comprises at least one wall comprising a first and a second surface. At least one film cooling hole extends through the wall between the first and second surfaces and has an outlet region at the second surface. The film cooling hole includes a first expansion section being a side diffusion portion and a second expansion section being a layback diffusion portion, wherein the side diffusion portion is upstream and spaced from the layback diffusion portion.

What is claimed is: 
     
       1. A component for a gas turbine engine comprising:
 a hot side exposed to a hot air flow; 
 a cool side exposed to a cooling air flow; 
 a film hole passage extending between the cool side and the hot side with an inlet on the cool side and an outlet on the hot side, the film hole passage defining a diameter, the film hole passage further defining a side diffusion portion defining a side diffusion length between a start of the side diffusion portion and the outlet, and a layback diffusion portion defining a layback diffusion length between a start of the layback diffusion portion and the outlet, wherein the side diffusion length is greater than the layback diffusion length and the layback diffusion portion begins at a point upstream of the outlet. 
 
     
     
       2. The component of  claim 1  wherein the side diffusion portion is upstream and spaced from the layback diffusion portion. 
     
     
       3. The component of  claim 1  wherein the side diffusion portion defines a side diffusion angle, α, relative to a centerline for the film hole passage, and the side diffusion angle is less than 12.5 degrees. 
     
     
       4. The component of  claim 3  wherein the layback diffusion portion defines a layback diffusion angle, β, relative to a centerline for the film hole passage, and the layback diffusion angle is less than 12 degrees. 
     
     
       5. The component of  claim 4  wherein the layback diffusion length is less than 4 times the diameter. 
     
     
       6. The component of  claim 4  wherein the layback diffusion length is less than four times the diameter and the side diffusion length is less than 35 times the diameter. 
     
     
       7. The component of  claim 6  wherein the film hole passage has a diameter less than 0.48 inches. 
     
     
       8. A film hole passage for a component, with a cool and hot side, of a gas turbine engine having an inlet on the cool side, an outlet on the hot, a side diffusion portion, and a layback diffusion portion, wherein the side diffusion portion is upstream and spaced from the layback diffusion portion and the layback diffusion portion begins at a point upstream of the outlet. 
     
     
       9. The film hole passage of  claim 8  wherein the side diffusion portion defines a side diffusion angle, α, relative to a centerline for the film hole passage, and the side diffusion angle is less than 12.5 degrees. 
     
     
       10. The film hole passage of  claim 8  wherein the layback diffusion portion defines a layback diffusion angle, β, relative to a centerline for the film hole passage, and the layback diffusion angle is less than 12 degrees. 
     
     
       11. The film hole passage of  claim 8  wherein the side diffusion portion defines a side diffusion length, the layback diffusion portion defines a layback diffusion length, and side diffusion length is greater than then layback diffusion length. 
     
     
       12. The film hole passage of  claim 11  wherein the layback diffusion length is less than 4 times a diameter of the film hole passage. 
     
     
       13. The film hole passage of  claim 12  wherein the layback diffusion length is less than 4 times the diameter and the side diffusion length is less than 35 times the diameter. 
     
     
       14. The film hole passage of  claim 13  wherein the film hole passage has a diameter less than 0.48 inches. 
     
     
       15. The film hole passage of  claim 8  wherein the film hole has the following geometry:
 a) the side diffusion portion defines a side diffusion angle, α, relative to a centerline for the film hole passage, and the side diffusion angle is less than 12.5 degrees, 
 b) the layback diffusion portion defines a layback diffusion angle, β, relative to the centerline for the film hole passage, and the layback diffusion angle is less than 12 degrees, and 
 c) wherein the side diffusion portion defines a side diffusion length, the layback diffusion portion defines a layback diffusion length, and side diffusion length is greater than then layback diffusion length. 
 
     
     
       16. A film hole passage for a component, with a cool and hot side, having an inlet on the cool side, an outlet on the hot, a side diffusion portion, and a layback diffusion portion, wherein the side diffusion portion is upstream and spaced from the layback diffusion portion, and the layback diffusion portion defines a layback diffusion length which is less than 4 times a diameter of the film hole passage and the layback diffusion portion begins at a point upstream of the outlet. 
     
     
       17. The film hole passage of  claim 16  wherein the film hole has the following geometry:
 a) the side diffusion portion defines a side diffusion angle, α, relative to a centerline for the film hole passage, and the side diffusion angle is less than 12 degrees, 
 b) the layback diffusion portion defines a layback diffusion angle, β, relative to the centerline for the film hole passage, and the layback diffusion angle is less than 12.5 degrees, and 
 c) wherein the side diffusion portion defines a side diffusion length, the layback diffusion portion defines a layback diffusion length, and side diffusion length is greater than then layback diffusion length. 
 
     
     
       18. The film hole passage of  claim 17  wherein the layback diffusion length is less than 4 times the diameter and the side diffusion length is less than 35 times the diameter.